You don't mention what you are looking for in terms of a "running configuration file". In Unix/Linux there are many of these. Most of them can be found in the /etc directory or its subdirectories but not all of them are located in /etc.
On NVRAM.
Boot Configuration Data (BCD)
NVRAM is that router component in which start up configuration file is stored.
NVRAM
It will boot into ROMMON mode. It will ignore the start-up configuration file. It will look for the start-up configuration file on the TFTP server. It will attempt to load the start-up configuration file that is stored in NVRAM.
wr or copy running-config startup config
The running configuration file on S1 will be saved via TFTP to a file named tokyo-config.
The Motherboard configuration is stored in the BIOS setup
SDRAM
Configuration settings file can be viewed either in notepad or browser depending on the type of configuration file. If the configuration file has extension - "INI", then it can be viewed in notepad or textpad. If the configuration file has extension - "XML", then it can be viewed both in Notepad and Browser.
Configuration files are typically stored in the /etc directory. They can, of course, be anywhere the implementer wishes them to be as long as the process knows where to find them.
This command will allow you to copy a configuration from a TFTP server to the running configuration of a Cisco device. When you issue the command you will be prompted for further details about the TFTP server. The new configuration will replace the active one (or running configuration) and make any necessary changes.